Originally Posted by s0ssos

I would actual prefer airlines say actual flying time, because there is really no way to account for delays. There are many significant delays, and they measure in hours. How do you split that up into numbers for every day, when they don't happen every day on the same flight? Do you take, say 3 hours that happens once a week and divide it by 7 and add it?
How do you account for ATC, airport congestion? The past isn't a good predictor, as some airports just get busier and busier (like Newark. There was a good article about how it was a sleepy airport back in the day, now is massively overloaded)-forget where it was.